Fagus Sylvatica Research Articles

Long-Term Effects of Thinning in Sub-Mountainous Thermophilic Sessile Oak (Quercus petraea Mill.) and European Beech (Fagus sylvatica L.) Coppices in the Croatian Dinarides

Coppicing has been neglected in recent decades, leaving gaps in knowledge on silvicultural interventions, especially the long-term effects on coppices of Southeast Europe. The recent economic crisis, the sudden increase in energy prices, and the increased demand for assorted wood products have initiated higher interest in coppices in Croatia. Thus, our work aims to define the long-term effects of thinning in sessile oak (Quercus petraea (Matt.) Liebl.) and European beech (Fagus sylvatica L.) sub-mountainous thermophilic low coppices in the Croatian Dinarides. The experiment includes two localities with thinning and control plots. Thinning was performed in 2002, with 17.71% of wood volume removed in the European beech coppice and 26.09% in the sessile oak coppice. In 2020, 1276 trees were marked, measured (DBH, tree height, number of stems per stump), and assessed for vitality, origin, and six silvicultural features revealing tree quality. In 2022, trees were again measured (DBH, tree height) to gain data on tree growth. Conventional data analysis methods were used. The results show a statistically significant positive long-term effect of thinning on tree growth, stem, and crown features and support findings that thinning, by increasing growth and quality, is a necessary intervention in European beech and sessile oak low coppices. Thinning promoted the healthiest and best quality trees/stems, resulting in a more valuable range of wood products and the potential for higher income. It had a positive impact on tree growth regardless of the tree’s origin (seed or stump) and improved the growth and quality of trees among the supporting tree species. Short-term effects of thinning in trial plots suggested that thinning supported tree species diversity, but this effect diminished over time, showing no positive effect after twenty years. The study points to the need for more frequent thinning in coppices to support tree species diversity (i.e., to allow growth to less competitive tree species) but underlines the need for further research.

Enhancing economic multifunctionality without compromising multidiversity and ecosystem multifunctionality via forest enrichment.

Enriching tree species-poor and less productive forests by introducing economically valuable species is a strategy proposed for achieving multipurpose forest management. However, empirical evidence from managed and mature forests on the impact of this enrichment on ecological (multidiversity and ecosystem multifunctionality) and economic dimensions remains scarce, particularly when nonnative species are used. Here, we propose and test a framework that integrates economic multifunctionality, encompassing timber production-oriented goals and resistance against disturbances, with multidiversity and ecosystem multifunctionality in European beech forest stands enriched with conifers. Our results show that enriched beech forest stands (~80 years old) can provide high levels of economic multifunctionality without compromising multidiversity and ecosystem multifunctionality. In comparison to pure beech stands, enriched stands with Douglas-fir supported win-win-win situations for these three dimensions. Our findings contribute to the discussion of integrating biodiversity, ecosystem, and economic functions, providing empirical evidence for future forest management.

Tribological properties and related effects of compressed, thermally modified and wax-impregnated wood

AbstractThis paper develops a process for the preparation of modified wood with low friction and low wear for tribological applications such as self-lubricating bearings. Two types of wood, beech (Fagus sylvatica) and robinia (Robinia pseudoacacia), have been studied and the results compared with naturally lubricated native lignum vitae. The process developed consists of plasticisation followed by compression in a mould, thermal modification and subsequent wax impregnation. Plasticisation was carried out by conditioning the samples to a low equilibrium moisture content of 10%, followed by heating to a sample core temperature of 80 °C. This process protects the internal wood structure from mechanical damage during densification. After plasticisation, the wood was compressed in a press mould. A low springback effect (SBE), resulting in compression of up to 40%, was achieved by unloading the mould without opening it. This step optimises compressive strength and hardness. Subsequent heat treatment reduces thickness swelling by up to 85%. Finally, a wax impregnation was applied to reduce friction. Sliding wear tests on modified beech wood have shown that the lowest wear occurs in the cross-sectional orientation (load perpendicular to the fibre ends; rxt orientation). Sliding friction studies using a steel ball on a ball-on-disc tribometer showed that compressed and thermally modified samples impregnated with rapeseed wax or beeswax exhibited coefficients of friction in a range of 0.08 to 0.09. These values are almost four times lower than those of plain compressed wood and even lower than those of lignum vitae, which was used for plain bearings decades ago. This study clearly demonstrates the high potential of compressed, thermally modified and wax-impregnated wood.

TreeCompR: Tree competition indices for inventory data and 3D point clouds

Abstract In times of more frequent global change‐type droughts and associated tree mortality events, competition release is one silvicultural measure discussed to have an impact on the resilience of managed forest stands. Understanding how trees compete with each other is therefore crucial, but different measurement options and competition indices (CI) leave users with a difficult choice, as no single competition index has proven universally superior. To help users with the choice and computation of appropriate indices, we present the open‐source TreeCompR package, which handles 3D point clouds and classical forest inventory data, enabling the calculation of both innovative point cloud‐based indices and traditional distance‐dependent indices. It serves as a centralized platform for exploring and comparing different CIs, allowing users to test and select the most suitable CI for their specific research questions within a common interface. To evaluate the package, we used TreeCompR to quantify the competition situation of 307 European beech trees from 13 sites in Central Europe. Based on this dataset, we discuss the interpretation, comparability and sensitivity of the different indices to their parameterization and identify possible sources of uncertainty and ways to minimize them. The compatibility of TreeCompR with different data formats and different data collection methods makes it accessible and useful for a wide range of users, specifically ecologists and foresters. Due to the flexibility in the choice of input formats as well as the emphasis on tidy, well‐structured output, our package can easily be integrated into existing data‐analysis workflows both for 3D point cloud and classical forest inventory data.

The biogeochemical model Biome-BGCMuSo v6.2 provides plausible and accurate simulations of the carbon cycle in central European beech forests

Abstract. Process-based ecosystem models are increasingly important for predicting forest dynamics under future environmental conditions, which may encompass non-analogous climate coupled with unprecedented disturbance regimes. However, challenges persist due to the extensive number of model parameters, scarce calibration data, and trade-offs between the local precision and the applicability of the model over a wide range of environmental conditions. In this paper, we describe a protocol that allows a modeller to collect transferable ecosystem properties based on ecosystem characteristic criteria and to compile the parameters that need to be described in the field. We applied the procedure to develop a new parameterisation for European beech (Fagus sylvatica L.) for the Biome-BGCMuSo model, the most advanced member of the Biome-BGC family. For model calibration and testing, we utilised multiyear forest carbon data from 87 plots distributed across five European countries. The initial values of 48 new ecophysiological parameters were defined based on a literature review. The final values of six calibrated parameters were optimised for single sites as well as for multiple sites using generalised likelihood uncertainty estimation (GLUE) and model output conditioning that ensured plausible simulations based on user-defined ranges of carbon stock output variables (carbon stock in aboveground wood biomass, soil, and litter) and finding the intersections of site-specific plausible parameter hyperspaces. To support the model use, we tested the model performance by simulating aboveground tree wood, soil, and litter carbon across a large geographical gradient of central Europe and evaluated the trade-offs between parameters tailored to single plots and parameters estimated using multiple sites. Our findings indicated that parameter sets derived from single sites provided an improved local accuracy of simulations of aboveground wood, soil, and litter carbon stocks by 35 %, 55 %, and 11 % in comparison to the a priori parameter set. However, their broader applicability was very limited. A multi-site optimised parameter set, on the other hand, performed satisfactorily across the entire geographical domain studied here, including on sites not involved in the parameter estimation, but the errors were, on average, 26 %, 35 % and 9 % greater for the aboveground wood, soil, and litter carbon stocks than those obtained with the site-specific parameter sets. Importantly, model simulations demonstrated plausible responses across large-scale environmental gradients, featuring a clear production optimum of beech that aligns with empirical studies. These findings suggest that the model is capable of accurately simulating the dynamics of European beech across its range and can be used for more comprehensive experimentations.

Genome sequence resources from three isolates of the apple canker pathogen Neonectria ditissima infecting forest trees

Neonectria ditissima is a generalist ascomycete plant pathogen causing canker diseases on a variety of hardwood tree species and can cross-infect many of them. The fungus enters the plants through wounds throughout the year. N. ditissima is considered a major threat to apple production responsible for the fruit tree canker disease which damages trees and causes rotting of fruits in storage. Nearby forests and shelter belts can serve as source of inoculum for well-managed apple orchards. Thus, knowledge about the N. ditissima isolates infecting different host species is essential for designing integrated pest management strategies. Here, we describe the genomes of three N. ditissima isolates, Nd_iso34, Nd_iso35, and Nd_iso36, infecting European beech, American tulip tree, and American beech, respectively. We obtained genome assemblies of ca. 45 megabases for all isolates, covering 94% of the N. ditissima reference annotation, and 97% of the universal single-copy orthologs (BUSCOs). We conclude that these genome assemblies are a highly relevant resource considering the scarcity of genomic data available for N. ditissima.

Climatic Effects on the Growth of Fagus sylvatica L. in Mixed Stands with Pinus sylvestris L. in Lithuania

Climate change and warming will potentially profoundly affect forest growth and yield. However, climate change is not only a threat but also an opportunity for tree species to be more productive or colonize new territories where previously they were fragmented or absent. European beech (Fagus sylvatica L.) is a dominant and significant tree species in European forests with a pronounced ability to grow on a great variety of sites and to form mixtures with other tree species due to its shade tolerance. So far, only a few studies have analysed its growth and reaction to changing climatic conditions outside its natural gradient in the north. The aim of this study was therefore to clarify the main growth patterns and tree ring formation characteristics of beech (outside their natural distribution) in mixed stands with Scots pine (Pinus sylvestris L.) The analyses were carried out in two-layered stands in the western part of Lithuania with tree-ring data measured on stem disks collected at 1 m height that were available from shelter-cut thinning activities in a number of forest stands in the region. Our results show that higher temperatures during the summer months of July and August generally inhibited the radial growth of beech under given site conditions. In contrast, warmer late-autumn and cooler early-winter periods together with warmer springs positively affected the radial increments. Above-average precipitation during the vegetation period contributed to the beech producing additional amounts of radial increments. The increasing temperature trends of the summer months and decreasing monthly amounts of precipitation during the vegetation period in recent decades tend to have adverse effects on the ecological conditions for beech growth and vitality in Lithuania. Despite these results, the European beech successfully grows in the sample region and has produced 200 m3 ha−1 in the analysed stands.

Indiferentní reakce sazenic borovice lesní a buku lesního ošetřených hydroabsorbenty

Super-absorbents are expected to amend soils as they are capable of retaining water, which turns dry loose powdery substances (also capsule) into hydrogel. These were applied to prevent an artificial regeneration failure due to drought events. Four commercially-available products were mixed with soil from planting holes (the capsule was put to the soil) in order to support bare-root Scots pine and European beech seedlings after a spring planting on eleven clear-cut sites in 2020–2021. The plantations were designed as rows with 4 × 150 plants treated with four hydrogels plus 150 plants without hydrogel as a control. The performance evaluation of new plantations was based on attributes such as mortality/survival and relative height and root-collar diameter increments. The plants, which lost their initial size, due to pine weevil damage, dry tops and damage by game, were excluded from the evaluation. Besides the plant response to the applied super-absorbents, the planting operations were evaluated from economic point of view. The 2020 plantations showed higher mortality than 2021 ones; both years showed an excessive loss. The hydrogels did not help the plants to survive better compared to control and growth data also showed ambiguous results. Therefore, from commercial perspective, the application of all tested super-absorbents just increased the renewal costs.

What Quality Suffices for Nanopore Metabarcoding? Reconsidering Methodology and Ectomycorrhizae in Decaying Fagus sylvatica Bark as Case Study.

Nanopore raw read accuracy has improved to over 99%, making it a potential tool for metabarcoding. For broad adoption, guidelines on quality filtering are needed to ensure reliable taxonomic unit recovery. This study aims to provide those guidelines for a fungal metabarcoding context and to apply them to a case study of ectomycorrhizae in the decaying bark of Fagus sylvatica. We introduce the eNano pipeline to test two standard metabarcoding approaches: (1) Reference-based mapping leveraging UNITE's species hypothesis system (SH approach); (2) Constructing 98% OTUs (OTU approach). Our results demonstrate that both approaches are effective with Nanopore data. When using a reference database, we recommend strict mapping criteria rather than Phred-based filtering. Leveraging the SH-system further enhances reproducibility and facilitates cross-study communication. For the 98% OTUs, filtering reads at ≥Q25 is recommended. Our case study reveals that the decay gradient is a primary determinant of community composition and that specific mycorrhizal fungi colonize decaying bark. Complementing our metabarcoding results with root tip morphotypification, we identify Laccaria amethystina and Tomentella sublilacina as key ectomycorrhizae of saplings on decaying logs. These findings demonstrate that Nanopore sequencing can provide valuable ecological insights and support its broader use in fungal metabarcoding as read quality continues to improve.

Stress Responses to Bark Beetle Infestations among Pine (Pinus sylvestris), Fir (Abies alba), and Beech (Fagus sylvatica) Trees

Insect infestation triggers multiple defense responses in plants, both locally at the infection site and systemically throughout the plant, including the production of feeding deterrents, toxins, defensive proteins, enzymes, and secondary metabolites. Our study aimed to compare the endogenous levels of antioxidative enzymes, photosynthetic pigments, phytohormones, total phenols, and flavonoids in bark-beetle-infested and uninfested trees. We evaluated the surviving trees in bark-beetle-infested stands, assessing both the condition and defense of uninfested and infested beech (Fagus sylvatica), pine (Pinus sylvestris), and fir (Abies alba) trees. Sampling was performed at six affected sites in the Czech Republic, targeting trees that were resilient to significant health deterioration caused by abiotic and biotic factors. The results showed different levels of most of the measured compounds in the three species. Among all the tested species, photosynthetic pigment levels showed the strongest association with infestation status, which was generally lower in the infested plants. For chlorophyll a, extremely significant reductions were observed from 123 ± 20.6 to 101 ± 17.9 μg/g dry weight (DW) in pine, from 231 ± 33.1 to 199 ± 22.2 μg/g DW in beech, and from 60 ± 5.66 to 51.3 ± 6.27 μg/g DW in fir. In contrast, enzymatic activities indicated only isolated instances of significant association, whereas antioxidative properties (total phenolic content, flavonoids, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity) were not significantly associated with infestation status. There was a statistically significant increase in glutathione reductase activity in infested fir and pine trees. However, this difference was not statistically significant in beech. In contrast, a significant increase in superoxide dismutase activity was detected in infected beech trees. Phytohormones have emerged as the most diverse group of analyzed compounds. Cytokinins were the most distinct, with many of them being significantly increased in infested pines, whereas both beech and fir showed only one significant association. Additionally, derivatives of jasmonic acid also showed a distinct pattern of change associated with bark beetle infestation, with the levels of three out of the four analyzed jasmonates being significantly decreased in infested pines, whereas no effects were observed in beeches and firs. Notably, many phytohormones were significantly elevated in the infested pine, whereas both beech and fir exhibited only one significant association. Overall, the data showed that pines responded differently to bark beetles than to beeches or firs. The greatest changes in phytohormones were observed in pine, whereas the most significant changes in photosynthetic pigments were observed in beech and fir trees.

Bioprospecting Endophytic Fungi of Forest Plants for Bioactive Metabolites with Antibacterial, Antifungal, and Antioxidant Potentials.

The growing emergence of multi-drug resistant microbial strains has kept the scientific world searching for novel bioactive compounds with specific chemical characteristics. Accordingly, researchers have started exploring the understudied metabolites from endophytes as a new source of bioactive compounds. In this context, the current study was designed to evaluate the bioactive properties of endophytic fungi from the Mokrzański forest in Wrocław, Poland that have not yet been fully researched. Forty-three endophytic fungi were isolated from twelve distinct plants. Following their cultivation, fungal extracts were separately prepared from biomass and cell-free filtrates, and their antibacterial, antifungal (against human and plant pathogens), and antioxidant properties were examined. Five promising fungi after screening were identified to possess all of these activities. These strains and their respective plant hosts were Trichoderma harzianum BUK-T (Fagus sylvatica), Aspergillus ochraceus ROB-L1 (Robinia pseudoacacia), Chaetomium cochliodes KLON-L1, Fusarium tricinctum KLON-L2 (Acer platanoides), and Penicillium chrysogenum SOS-B2 (Pinus sylvestris). Moreover, gamma irradiation at several doses (Gy) was separately applied to the fungal cultures to study their effects on the recorded activities. Finally, compounds after preparative thin-layer chromatography fractionation of the five fungal strains were identified by GC-MS. These findings suggest that the isolated endophytic fungi could serve as novel sources of bioactive metabolites with antibacterial, antifungal, and antioxidant properties, potentially paving the way for future research and the development of new bioactive compounds.

Genomic variation of European beech reveals signals of local adaptation despite high levels of phenotypic plasticity

Local adaptation is key for ecotypic differentiation and species evolution. Understanding underlying genomic patterns can allow the prediction of future maladaptation and ecosystem stability. Here, we report the whole-genome resequencing of 874 individuals from 100 range-wide populations of European beech (Fagus sylvatica L.), an important forest tree species in Europe. We show that genetic variation closely mirrors geography with a clear pattern of isolation-by-distance. Genome-wide analyses for genotype-environment associations (GEAs) identify relatively few potentially adaptive variants after correcting for an overwhelming signal of statistically significant but non-causal GEAs. We characterize the single high confidence genomic region and pinpoint a candidate gene possibly involved in winter temperature adaptation via modulation of spring phenology. Surprisingly, allelic variation at this locus does not result in any apparent fitness differences in a common garden. More generally, reciprocal transplant experiments across large climate distances suggest extensive phenotypic plasticity. Nevertheless, we find indications of polygenic adaptation which may be essential in natural ecosystems. This polygenic signal exhibits broad- and fine-scale variation across the landscape, highlighting the relevance of spatial resolution. In summary, our results emphasize the importance, but also exemplify the complexity, of employing natural genetic variation for forest conservation under climate change.

Early-successional species show higher tolerance of drought than late-successional species across Europe.

Climate change is exacerbating forest disturbances through more frequent and more intense droughts and fires, undermining their ability to recover from such disturbances. The response of fast-growing early-successional species to drought is poorly understood, despite their key role in ecological succession and their ability to enhance ecosystem resilience. Here, we compared the growth responses to drought events of three early-successional species (silver birch, black poplar, and Scots pine) with that of one late-successional species (European beech) across their natural distribution ranges in Europe. We used tree-ring widths of 6340 trees from 109 forest sites to establish species-specific tree-ring chronologies. We then used multiple linear regressions to analyze which climatic or growth variables (pre-drought growth and growth during drought) best explained the tree responses to drought. Silver birch, Scots pine, and black poplar showed superior drought tolerance, with a slight, non-significant growth reduction under drought, whereas European beech showed a significant decrease in growth. The variables that influenced growth during and after the drought were species-specific. Annual precipitation and growth variables were key predictors of post-drought growth for Scots pine, black poplar, and European beech. Scots pine and silver birch grew better with increasing latitude, i.e., in Northern Europe than in Central Europe, while European beech and black poplar showed more growth at sites with high precipitation during the vegetation and dormant period, respectively. This study provides insights into the drought tolerance of early-successional species and highlights their ability to promote ecological succession and facilitate the transition to drought-resistant, late-successional forest ecosystems.

No Future Growth Enhancement Expected at the Northern Edge for European Beech due to Continued Water Limitation.

With ongoing global warming, increasing water deficits promote physiological stress on forest ecosystems with negative impacts on tree growth, vitality, and survival. How individual tree species will react to increased drought stress is therefore a key research question to address for carbon accounting and the development of climate change mitigation strategies. Recent tree-ring studies have shown that trees at higher latitudes will benefit from warmer temperatures, yet this is likely highly species-dependent and less well-known for more temperate tree species. Using a unique pan-European tree-ring network of 26,430 European beech (Fagus sylvatica L.) trees from 2118 sites, we applied a linear mixed-effects modeling framework to (i) explain variation in climate-dependent growth and (ii) project growth for the near future (2021-2050) across the entire distribution of beech. We modeled the spatial pattern of radial growth responses to annually varying climate as a function of mean climate conditions (mean annual temperature, mean annual climatic water balance, and continentality). Over the calibration period (1952-2011), the model yielded high regional explanatory power (R2 = 0.38-0.72). Considering a moderate climate change scenario (CMIP6 SSP2-4.5), beech growth is projected to decrease in the future across most of its distribution range. In particular, projected growth decreases by 12%-18% (interquartile range) in northwestern Central Europe and by 11%-21% in the Mediterranean region. In contrast, climate-driven growth increases are limited to around 13% of the current occurrence, where the historical mean annual temperature was below ~6°C. More specifically, the model predicts a 3%-24% growth increase in the high-elevation clusters of the Alps and Carpathian Arc. Notably, we find little potential for future growth increases (-10 to +2%) at the poleward leading edge in southern Scandinavia. Because in this region beech growth is found to be primarily water-limited, a northward shift in its distributional range will be constrained by water availability.

Decline of beech trees in a Mediterranean forest is associated with high rhizosphere oomycete diversity

In the last decades, tree decline in European beech forests has been related to extreme climatic events and with the activity of parasitic oomycetes such as Phytophthora species. In Spain, little is known about the association of beech decline and soil oomycete composition. We hypothesized that the weakening of beech trees is associated with the activity and proliferation of parasitic oomycetes. We studied the rhizosphere oomycete community of large beech trees located in one of the southernmost beech forests in Europe. From soil samples collected in the rhizosphere, we used a metabarcoding approach to explore the oomycete community associated to asymptomatic and declining trees. We also studied fine root parameters in both groups of trees. A total of 99 oomycete amplicon sequence variants (ASVs) were detected. Higher diversity and richness of oomycetes were observed in declining than in asymptomatic trees. The oomycete composition also differed between the two groups of trees. Declining trees showed lower fine root biomass and root density than asymptomatic trees, and root density was negatively correlated with the abundance of Pythium ASV counts. The genus Phytophthora, associated with beech decline in central Europe, was underrepresented in the oomycete community. The results suggest that decline-associated processes in beech trees are related with fine root weakening and loss which probably facilitates the entrance and colonization of opportunistic oomycete microbes. Although members in the genus Pythium do not seem to be a primary factor on beech decline, they probably contribute to the chronic decline of Fagus sylvatica trees.

Comparing Wettability and Surface Free Energy of False Heartwood, Ripe Wood and Sapwood in Beech (Fagus sylvatica L.)

Comparing Wettability and Surface Free Energy of False Heartwood, Ripe Wood and Sapwood in Beech (Fagus sylvatica L.)

Site conditions rather than provenance drive tree growth, climate sensitivity and drought responses in European beech in Germany

Ongoing climate change and associated extreme events strongly impact the growth and vitality of forest ecosystems in Europe. Because of its’ high drought sensitivity, European beech, which is considered as climax tree species in large parts of Central Europe, may specifically suffer. Hence, recent studies increasingly focus on the resistance and resilience of beech growth to climate change. Intra-specific variations in growth responses by comparing different beech provenances, however, received less attention, as did the question whether provenance selection can be used to mitigate potential future negative impacts of climate change. Therefore, we here investigated 24 provenances belonging to the International Beech Provenance Trial growing at three sites in Germany along a latitudinal gradient (study sites are referred to as ’North’, ‘Center’, ‘South’). Specifically, we compared tree-ring width (TRW), diameter breast height (DBH), climate-growth relationships, as well as drought resistance and resilience in the extreme years 2003 and 2018. Large differences in growth performance were observed between the three study sites. At site North, beech trees showed the highest DBH and TRW. Tree growth was predominantly driven by previous-year October and current-year winter temperature, whereas growth at sites Center and South was significantly impacted by summer SPEI and constrained by precipitation in late winter and early June, respectively. Overall, drought responses in 2003 were less variable than in 2018. We found increasing resistance and decreasing resilience from the wetter North to the drier South, but with minimal differences between the Center and the South. Whereas differences between study sites were large, provenance differentiation within sites was comparably low, substantiating that beech is a highly plastic tree species. Even though some provenances were found to perform slightly better or worse, differences were not statistically significant and show unclear patterns. Hence, we conclude that climate change will affect beech forests in Europe mainly depending upon site conditions, and that provenance selection may not ensure superior growth performance.

The White-backed Woodpecker (Dendrocopos leucotos) as an umbrella species for threatened saproxylic beetle communities in Central European beech forests

The umbrella species concept is a popular conservation planning tool which postulates that conservation schemes targeting a specific species will indirectly benefit many other sympatric species. In Scandinavia and Central Europe, the White-backed Woodpecker (Dendrocopos leucotos) is considered an umbrella species for woodland birds and cryptogam species of conservation concern. Whether this also applies to saproxylic beetles, a group of high conservation concern, remains open. Therefore, we tested that umbrella function in Central European beech forests that are currently recolonized by this woodpecker. Relying on radiotracking data, we compared saproxylic beetle communities within the breeding home ranges of White-backed Woodpeckers (high and low activity of the bird) against forests with ascertained absence of the bird (control). Bayesian inference for linear regressions identified that species richness of threatened saproxylic beetles was 1.51 (lower and upper 5 % PPCrI=[1.09; 2.01]) times higher in sites with high White-backed Woodpecker activity compared to the control. Community composition analyses on threatened saproxylic beetles showed a reduced β-diversity at low and high White-backed Woodpecker sites compared to the control. Finally, an indicator species analysis showed that 17 saproxylic beetle species, including 4 threatened species, were positively associated with White-backed Woodpecker’s breeding home ranges, while only 3 species, but no threatened species, were associated with the control sites. Overall, our results suggest that the White-backed Woodpecker plays the role of an umbrella species for threatened saproxylic beetle communities, opening new opportunities for conservation planning in European beech forests.

Exploring the effects of the assisted transfer of European beech (Fagus sylvatica L.) provenances in the Romanian Carpathians

The genetic inheritance of a tree species is fully expressed in the phenotype only when its ecological requirements are accomplished. Therefore, genetic tests provide the opportunity to simulate the change in the environment and determine the most suitable site conditions for specific populations. In light of the unpredictable climate conditions resulting from rapid environmental changes, the current study investigated possible signs of adaptation and productivity of European beech in the Romanian Carpathian region. For this purpose, the tree growth and stability performances, as well as the transfer effect, were examined in 17 international beech provenances tested in two different environments for 27 years. Growth and stability performances were evaluated using tree height (Th), breast height diameter (DBH), and survival (S). In the case of the transfer analyses, the ecodistance approach was applied. According to the results, the average of S was 13% higher in the Carbunari provenance trial, and DBH was higher in the Sacele trial by 15%, while no noticeable differences were registered for Th. The best-performing provenances were those originating from similar site conditions to the Romanian test sites, and the transfer function detected the sensitivity of beech provenances to increasing temperature. The general transfer response of provenances revealed a similar performance across sites and suggested that provenances exhibited adaptation and acclimation to the test environments from Romanian Carpathians.

Silicon Modifies Photosynthesis Efficiency and hsp Gene Expression in European Beech (Fagus sylvatica) Seedlings Exposed to Drought Stress.

Background: Climate change is leading to severe and long-term droughts in European forest ecosystems. can have profound effects on various physiological processes, including photosynthesis, gene expression patterns, and nutrient uptake at the developmental stage of young trees. Objectives: Our study aimed to test the hypothesis that the application of silica (SiO2) influences photosynthetic efficiency and gene expression in 1- to 2-year-old Fagus sylvatica (L.) seedlings. Additionally, we aimed to assess whether silicon application positively influences the structural properties of leaves and roots. To determine whether the plant physiological responses are genotype-specific, seedlings of four geographically different provenances were subjected to a one-year evaluation under greenhouse conditions. Methods: We used the Kruskal-Wallis test followed by Wilcoxon's test to evaluate the differences in silicon content and ANOVA followed by Tukey's test to evaluate the physiological responses of seedlings depending on treatment and provenance. Results: Our results showed a significantly higher Si content in the roots compared with the leaves, regardless of provenance and treatment. The most significant differences in photosynthetic performance were found in trees exposed to Si treatment, but the physiological responses were generally nuanced and provenance-dependent. Expression of hsp70 and hsp90 was also increased in leaf tissues of all provenances. These results provide practical insights that Si can improve the overall health and resilience of beech seedlings in nursery and forest ecosystems, with possible differences in the beneficial role of silicon application arising from the large differences in wild populations of forest tree species.